The Clinical Syndrome

Scapulocostal syndrome consists of a constellation of symptoms including unilateral pain and associated paresthesias at the medial border of the scapula, referred pain radiating from the deltoid region to the dorsum of the hand, and decreased range of motion of the scapula ( Fig. 36.1 ). Scapulocostal syndrome is commonly referred to as traveling salesman’s shoulder, because it is frequently seen in individuals who repeatedly reach backward to retrieve something from the back seat of a car ( Fig. 36.2 ). Scapulocostal syndrome is an overuse syndrome caused by repeated improper use of the muscles of scapular stabilization—the levator scapulae, pectoralis minor, serratus anterior, rhomboids, and, to a lesser extent, infraspinatus and teres minor.

Scapulocostal syndrome involves unilateral pain and associated paresthesias at the medial border of the scapula, referred pain radiating from the deltoid region to the dorsum of the hand, and decreased range of motion of the scapula.

(From Waldman SD. Atlas of pain management injection techniques. 2nd ed. Philadelphia: Saunders; 2007.)

Scapulocostal syndrome is also called traveling salesman’s shoulder because it is frequently seen in individuals who repeatedly reach backward to retrieve something from the back seat of a car.

Scapulocostal syndrome is a chronic myofascial pain syndrome, and the sine qua non of myofascial pain syndrome is the finding of myofascial trigger points on physical examination. Although these trigger points are generally localized to the part of the body affected, the pain is often referred to other areas. This referred pain may be misdiagnosed or attributed to other organ systems, thus leading to extensive evaluation and ineffective treatment. Mechanical stimulation of the trigger point by palpation or stretching produces both intense local pain and referred pain. In addition, involuntary withdrawal of the stimulated muscle, called a jump sign, is often seen and is characteristic of myofascial pain syndrome. Almost all patients with scapulocostal syndrome have a prominent infraspinatus trigger point, which is best demonstrated by having the patient place the hand of the affected side over the deltoid of the opposite shoulder ( Fig. 36.3 ). This maneuver laterally rotates the affected scapula and allows palpation and subsequent injection of the infraspinatus trigger point. Other trigger points along the medial border of the scapula may be present and may be amenable to injection therapy.

The infraspinatus trigger point can be demonstrated by having the patient place the hand of the affected side over the deltoid of the opposite shoulder.

Taut bands of muscle fibers are often identified when myofascial trigger points are palpated. Despite this consistent physical finding, the pathophysiology of the myofascial trigger point remains elusive, although trigger points are believed to result from microtrauma to the affected muscle. This trauma may occur from a single injury, repetitive microtrauma, or chronic deconditioning of the agonist and antagonist muscle unit.

In addition to muscle trauma, various other factors seem to predispose patients to develop myofascial pain syndrome. For instance, a weekend athlete who subjects his or her body to unaccustomed physical activity may develop myofascial pain syndrome. Poor posture while sitting at a computer or while watching television has also been implicated as a predisposing factor. Previous injuries may result in abnormal muscle function and lead to the development of myofascial pain syndrome. All these factors may be intensified if the patient also suffers from poor nutritional status or coexisting psychological or behavioral abnormalities, including chronic stress and depression. The muscle groups involved in scapulocostal syndrome seem to be particularly susceptible to stress-induced myofascial pain syndrome.

Stiffness and fatigue often coexist with pain, and they increase the functional disability associated with this disease and complicate its treatment. Myofascial pain syndrome may occur as a primary disease state or in conjunction with other painful conditions, including radiculopathy and chronic regional pain syndromes. Psychological or behavioral abnormalities, including depression, frequently coexist with the muscle abnormalities, and management of these psychological disorders is an integral part of any successful treatment plan.